Rules, Cascodes and Relief
Hey Harry,
Thank you for your vote of confidence on the Intro forum! It's much easier to be moderate at 50 than at 30! Do you find this???????
Bernhard,
To refer to the comment you passed on Intros; back to the Cascode later. You are a gifted, highly articulate man. I recently visited your website and looked at your incredible phono pickup. Man, that's art! Just wonderful! And your enthusiasm for vinyl and CAD drawing is palpable; clearly visible on your site and very impressive to me, a CADCAM troglodyte.
However, at the risk of upsetting you, you should think about lightening up. You feel too intently, and maybe you think too much about these relatively unimportant things. Your post listing the dos and don'ts makes good common sense, but it is prescriptive, and best left unsaid. Rules can create resentment, and I wouldn't like to have all my posts put through those rules to check correctness. I have no wish to start a flame war, and never will (although I like to stir occasionally!) but believe me, if it happens, I'm outa here. I have survived many flame wars on joenet only by remaining silent; flames are fanned only by emotional responses. The brain damage is much worse if you respond; humans are often incensed by disagreement, yet they are drawn to it like moths to a flame. Leave the email unanswered if you don't agree with it; this works every time, as time dilutes everything.
Now, may I return to my hobby horse, that pesky cascode? I am like a dog with a bone on this one, I love a friendly debate, and since I've built it and measured it, I know its performance, and the gain is huge. This is in sharp contrast to the diff pair, whose gain is trivial by comparison.
I don't believe it's a diff pair because a diff pair uses identical transistor types. These are npn and pnp, cat and dog!
Now, Harry, you must get in your Miata and crank it up to 6000rpm! This may cause you to rethink your topology recognition skills.........
Cheers,
Hugh
www.printedelectronics.com
Hey Harry,
Thank you for your vote of confidence on the Intro forum! It's much easier to be moderate at 50 than at 30! Do you find this???????
Bernhard,
To refer to the comment you passed on Intros; back to the Cascode later. You are a gifted, highly articulate man. I recently visited your website and looked at your incredible phono pickup. Man, that's art! Just wonderful! And your enthusiasm for vinyl and CAD drawing is palpable; clearly visible on your site and very impressive to me, a CADCAM troglodyte.
However, at the risk of upsetting you, you should think about lightening up. You feel too intently, and maybe you think too much about these relatively unimportant things. Your post listing the dos and don'ts makes good common sense, but it is prescriptive, and best left unsaid. Rules can create resentment, and I wouldn't like to have all my posts put through those rules to check correctness. I have no wish to start a flame war, and never will (although I like to stir occasionally!) but believe me, if it happens, I'm outa here. I have survived many flame wars on joenet only by remaining silent; flames are fanned only by emotional responses. The brain damage is much worse if you respond; humans are often incensed by disagreement, yet they are drawn to it like moths to a flame. Leave the email unanswered if you don't agree with it; this works every time, as time dilutes everything.
Now, may I return to my hobby horse, that pesky cascode? I am like a dog with a bone on this one, I love a friendly debate, and since I've built it and measured it, I know its performance, and the gain is huge. This is in sharp contrast to the diff pair, whose gain is trivial by comparison.
I don't believe it's a diff pair because a diff pair uses identical transistor types. These are npn and pnp, cat and dog!
Now, Harry, you must get in your Miata and crank it up to 6000rpm! This may cause you to rethink your topology recognition skills.........
Cheers,
Hugh
www.printedelectronics.com
Sonny,
There are a number of acronyms (words made up of letters from other words) that are in common use on the web.
IMO= In My Opinion
IMHO= In My Humble Opinion
There are scads of these things out there and, frankly, I don't know what all of them mean, myself (used to be that LOL meant Lots Of Luck, now it means Lots Of Laughs--I don't even try to keep up with the changes). People use them because they're too lazy to type what they're actually saying. To me, (IMHO, of course) they look childish. One of the kids was in this phase of spelling the word 'anyway' as 'ne-way' for a while. I think that's over. Hope so, ne-way.
The problem is that the blasted things take on a life of their own and someone who is fluent in this argot can produce a sentence that is pretty opaque to someone not versed in the cliches; looks like alphabet soup.
Given that the purpose of language is to communicate, my feeling is that these abbreviations are counterproductive, serving only to separate those who are 'cool' from those who aren't. With the exception of the common acronyms within electronics (FET, NPN, etc.), I prefer not to use them. I don't even use terms like 'trannie' as it means transformer to some people and transistor to others. English is a hard enough language to learn without gunking it up with a bunch of artificial things simply because people are too lazy to type a few more letters.
Grey
...and I still say it's pathetic that some of the foreign, non-English-speaking members of this site are easier to read, both in terms of grammar and spelling, than some of the Aussies, Brits, and Yanks, for whom English is--or should be--the native language.
There are a number of acronyms (words made up of letters from other words) that are in common use on the web.
IMO= In My Opinion
IMHO= In My Humble Opinion
There are scads of these things out there and, frankly, I don't know what all of them mean, myself (used to be that LOL meant Lots Of Luck, now it means Lots Of Laughs--I don't even try to keep up with the changes). People use them because they're too lazy to type what they're actually saying. To me, (IMHO, of course) they look childish. One of the kids was in this phase of spelling the word 'anyway' as 'ne-way' for a while. I think that's over. Hope so, ne-way.
The problem is that the blasted things take on a life of their own and someone who is fluent in this argot can produce a sentence that is pretty opaque to someone not versed in the cliches; looks like alphabet soup.
Given that the purpose of language is to communicate, my feeling is that these abbreviations are counterproductive, serving only to separate those who are 'cool' from those who aren't. With the exception of the common acronyms within electronics (FET, NPN, etc.), I prefer not to use them. I don't even use terms like 'trannie' as it means transformer to some people and transistor to others. English is a hard enough language to learn without gunking it up with a bunch of artificial things simply because people are too lazy to type a few more letters.
Grey
...and I still say it's pathetic that some of the foreign, non-English-speaking members of this site are easier to read, both in terms of grammar and spelling, than some of the Aussies, Brits, and Yanks, for whom English is--or should be--the native language.
Grey,
I agree that the use of cyber abbreviations in public forums can indeed be counterproductive and downright confusing for those who do not use such short hand frequently. As such i try to limit my use of these abbreviations on these forums only using the occasional LOL or IMHO. I do however spend a large period of time communicating with people from all over the world via IRC and similar technologies where such short hand can indeed be a valuable resource.
With regard to the grammar and spelling issues, i agree that it is rather silly that many of us who have english as our native tongue can not even learn to use it as well as those to whom english is often a third or fourth language.
Sonny,
Just a few more abbreviations you might see....
WRT - With Respect To
IME - In My Experience
Regards,
AudioFreak.
I agree that the use of cyber abbreviations in public forums can indeed be counterproductive and downright confusing for those who do not use such short hand frequently. As such i try to limit my use of these abbreviations on these forums only using the occasional LOL or IMHO. I do however spend a large period of time communicating with people from all over the world via IRC and similar technologies where such short hand can indeed be a valuable resource.
With regard to the grammar and spelling issues, i agree that it is rather silly that many of us who have english as our native tongue can not even learn to use it as well as those to whom english is often a third or fourth language.
Sonny,
Just a few more abbreviations you might see....
WRT - With Respect To
IME - In My Experience
Regards,
AudioFreak.
My last post (12-13 posts up) described a two-stage topology with a CE-stage loaded with 5 ohms on the collector, hooked up with a CB-stage. My point of argument is that this is not very far from what we do with a cascode, where the collector is loaded down with the input impedance of the CB-stage. First we kill all the gain of the first stage with a few ohms on the collector, then we use a high gain stage to restore the gain again.
Back to listening. What I hear with cascodes is a kind of vividness when transients are processed. A vivid sound is often the result of high uncontrolled gain. Now, doesn´t that fit a CB-stage ? This would imply that the sound of cascodes comes from the CB-stage rather than the CE-stage.
Regards
Syl
Back to listening. What I hear with cascodes is a kind of vividness when transients are processed. A vivid sound is often the result of high uncontrolled gain. Now, doesn´t that fit a CB-stage ? This would imply that the sound of cascodes comes from the CB-stage rather than the CE-stage.
Regards
Syl
dare to be differential
A cascode can be built with the same type of devices or different types in the case of an inverted cascode. A differential amp responds to a differential input and ignors common mode input signals (for the most part, it is not perfect in common mode rejection) If identical load resistors are connected to the collectors of a complementary diff amp, a pnp and npn collected at the emitters, the outputs will be equal and out of phase signals just like a long tailed diff pair. I can't see any difference in terms of basic input to output performance but only differences in biasing and DC levels.
H.H.
A cascode can be built with the same type of devices or different types in the case of an inverted cascode. A differential amp responds to a differential input and ignors common mode input signals (for the most part, it is not perfect in common mode rejection) If identical load resistors are connected to the collectors of a complementary diff amp, a pnp and npn collected at the emitters, the outputs will be equal and out of phase signals just like a long tailed diff pair. I can't see any difference in terms of basic input to output performance but only differences in biasing and DC levels.
H.H.
Dare to be Deferential......
Harry, you got me........
If, however, we have the same current flowing through both transistors such that both share the same peaks and troughs, then can this truly be called differential? The word implies conjugate, surely; as one current through one device increases, then the other decreases. This is the differential action implicit in the use of the word, I suspect.
In any event, in my view the exact description is not the issue. This beast has very high open loop gain, and is thus useful for topologies which feature lashes of global feedback. In this sense, the building block has promise for fostering high bandwidth, low source impedance amplifiers, and this is what I wanted to emphasize.
The primary issue with global feedback is the quality of the voltage division at the feedback node; it is seriously compromised by the highly distortive capacitor used as the DC blocker. Of course, this does not apply with JFET diff pairs. Thus I believe that voltage amplifiers of this configuration are useful as building blocks, and would like to draw attention to them in this forum since they might be made to work in otherwise conventional amplifiers.
Cheers,
Hugh
www.printedelectronics.com
Harry, you got me........
If, however, we have the same current flowing through both transistors such that both share the same peaks and troughs, then can this truly be called differential? The word implies conjugate, surely; as one current through one device increases, then the other decreases. This is the differential action implicit in the use of the word, I suspect.
In any event, in my view the exact description is not the issue. This beast has very high open loop gain, and is thus useful for topologies which feature lashes of global feedback. In this sense, the building block has promise for fostering high bandwidth, low source impedance amplifiers, and this is what I wanted to emphasize.
The primary issue with global feedback is the quality of the voltage division at the feedback node; it is seriously compromised by the highly distortive capacitor used as the DC blocker. Of course, this does not apply with JFET diff pairs. Thus I believe that voltage amplifiers of this configuration are useful as building blocks, and would like to draw attention to them in this forum since they might be made to work in otherwise conventional amplifiers.
Cheers,
Hugh
www.printedelectronics.com
Re: Rules
Hugh,
you find me indeed upset.
Then why the heck do you carry flames to a new haystack? Let the mess happen in the thread it begun and do not pollute other threads.
Did you contribute to this thread with your remarks? Methinks not, methinks it would have contriibuted the thread it belongs to, and if i had read the same chewing-out there, you bet my tone replying would have been completely different.
Rest to be discussed off-line.
All,
the list Hugh is referring to was a quick'n'dirty one, instantaneously thought-out from experiences of the past, not something i copied from my red book. Nevertheless i can stand by it, apart from the fact that it is incomplete.
My mistake is indeed that i sometimes see things too serious. But i have observed too often how it ends up if something happens that i find me together with others not agreeing with and we all slink away like cowards and let the bullies dominate the territory. We live in a time where political correctness seems to be one of the highest ethical values. To me "political correctness is another term for cowardice" (which of course does not keep me from struggling not to hurt others).
If I sense something menaced i like very much (like this forum), i do not stay mute as i used to do, i fight for it. And i am willing to take bruises and worse.
I do believe that a funny, happy, mutually respectful place does not stay that way for free. I do believe that if bullying hurts the bully, he thinks twice before bullying.
Danger: the fighting too can damage what i am intending to defend, particularly if the covert goal was to attract attention. A walk on a rope ...
However, may i be considered as a lecturer, make that a smartasssss, if every 2nd participant of this ruckus has not only read it but got thinking about it, i have reached my goal and you all can call me worse names in exchange for that
Today i have read syl's introduction, particularly the 1st 2 lines. Quite a bold thing to say so in an introduction. Yet i have to agree to 100% (fervently hoping he does not mean me with the odd guy )
I have to agree today, i would have objected fervently the week i joined. Which is not long ago.
Hugh,
you find me indeed upset.
Then why the heck do you carry flames to a new haystack? Let the mess happen in the thread it begun and do not pollute other threads.
Did you contribute to this thread with your remarks? Methinks not, methinks it would have contriibuted the thread it belongs to, and if i had read the same chewing-out there, you bet my tone replying would have been completely different.
Threats are promises. You might face the need to keep that promise.
Rest to be discussed off-line.
All,
the list Hugh is referring to was a quick'n'dirty one, instantaneously thought-out from experiences of the past, not something i copied from my red book. Nevertheless i can stand by it, apart from the fact that it is incomplete.
My mistake is indeed that i sometimes see things too serious. But i have observed too often how it ends up if something happens that i find me together with others not agreeing with and we all slink away like cowards and let the bullies dominate the territory. We live in a time where political correctness seems to be one of the highest ethical values. To me "political correctness is another term for cowardice" (which of course does not keep me from struggling not to hurt others).
If I sense something menaced i like very much (like this forum), i do not stay mute as i used to do, i fight for it. And i am willing to take bruises and worse.
I do believe that a funny, happy, mutually respectful place does not stay that way for free. I do believe that if bullying hurts the bully, he thinks twice before bullying.
Danger: the fighting too can damage what i am intending to defend, particularly if the covert goal was to attract attention. A walk on a rope ...
However, may i be considered as a lecturer, make that a smartasssss, if every 2nd participant of this ruckus has not only read it but got thinking about it, i have reached my goal and you all can call me worse names in exchange for that
Today i have read syl's introduction, particularly the 1st 2 lines. Quite a bold thing to say so in an introduction. Yet i have to agree to 100% (fervently hoping he does not mean me with the odd guy
)I have to agree today, i would have objected fervently the week i joined. Which is not long ago.
Open Loop Pain
Jocko,
This hurts; I did this work about four years back. Let's see, we measured at 1KHz with 6mA, CCS, PNP at the bottom, NPN cascoding, driven from a PNP diff pair. A green 1V95 LED was used as the voltage reference for the upper base.
Bandwidth was tricky to measure, but oscillation was around 5MHz if the lag compensation was under about 22pF.
The circuit was inserted into the voltage amplifier of a conventional Bailey topology (without the output stage). The Zout was 3 ohms as I recall, indicating a huge feedback factor, but I didn't do the math. Given that the same topology with a single transistor in common emitter at the voltage amp gives a Zout of around 35 ohms, indications are that this delivers an OLG at least an order of magnitude higher.
It's worth noting that stability can be improved at the cost of gain by degenerating resistively between the emitters. This techique is extremely effective, and only about 10R is required to pull back OLG by about half.
Jocko, that's the sum total of my memory. It's an interesting circuit block, and shows promise, but of course it must be said that the use of lashes of global negative feedback is extremely politically incorrect, and you risk invoking the marketing kiss of death if you implement this in a retail product........
Jocko, I hope this sates an inquiring mind! Harry, I'd be interested in PSpice analysis. I don't have the program, sadly.
Cheers,
Hugh
www.printedelectronics.com
Jocko,
This hurts; I did this work about four years back. Let's see, we measured at 1KHz with 6mA, CCS, PNP at the bottom, NPN cascoding, driven from a PNP diff pair. A green 1V95 LED was used as the voltage reference for the upper base.
Bandwidth was tricky to measure, but oscillation was around 5MHz if the lag compensation was under about 22pF.
The circuit was inserted into the voltage amplifier of a conventional Bailey topology (without the output stage). The Zout was 3 ohms as I recall, indicating a huge feedback factor, but I didn't do the math. Given that the same topology with a single transistor in common emitter at the voltage amp gives a Zout of around 35 ohms, indications are that this delivers an OLG at least an order of magnitude higher.
It's worth noting that stability can be improved at the cost of gain by degenerating resistively between the emitters. This techique is extremely effective, and only about 10R is required to pull back OLG by about half.
Jocko, that's the sum total of my memory. It's an interesting circuit block, and shows promise, but of course it must be said that the use of lashes of global negative feedback is extremely politically incorrect, and you risk invoking the marketing kiss of death if you implement this in a retail product........
Jocko, I hope this sates an inquiring mind! Harry, I'd be interested in PSpice analysis. I don't have the program, sadly.
Cheers,
Hugh
www.printedelectronics.com
In the A75 paper, cascoding the output stage is one of the choice. But the authors have decided not to use cascode in the output stage, because it produces "Lack of Dynamic" sound, like the same with Threshold amp which uses the same output stage cascode. What is behind this "Lack of Dynamic"?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.